Fluid diaphragm



Sept' 13, 1949 H. HARRISON 2,481,660

FLUID DIAPHRAGM Filed NOV. 7, 1946 Hen/ y, Har/A900 I N V E N TORATTORNEYS Patented Sept. 13,; 1949 UNITED i s'rifrrzsl PATENT o FFIC'EQHenry Harrison, Rochester, NaY., assignor.to Eastman Kodak Company,Bochester, N. Y., a corporation of New Jersey s Application November 7,194s, serialNo. 708,394

This invention relates to photography and more vparticularly -todiaphra'gms.k One object of my invention 'is to provide a diaphragm forcontrolling a beam of light, the effective aperture of the diaphragmbeingY controlled by pressure against opticalelements between whichthere is a layer of fluid selected` to obstruct light rays. Another ob-4jectoimy invention isto provide a iiuid dia- .phragm which 'can bereadily controlled to vary the 'diaphragm aperture and which can .bereadfily.' operated lby remote control. A still Vfurther ,objectof myYinvention is to provide a fluid diaphragrnV whichzis particularlysuitable for controlling alight'beam passing through an optical system.`A still further object of my invention is] to provide `a relatively`inexpensive diaphragm .which may control either certain colored lightiraysyor all of the light rays passing through opticalv apparatus, andother objects will appear from the following speciiication, the novelfeatures being particularly pointed out in the claims -atthe endthereof.

It is customary to providemetal'diaphragms consisting of; plates withapertures in them, or

consisting of two or more krelatively movable plates or diaphragm leavesAwhich can be manually moved to vary the-size of an aperture through-which light rays may pass. However, such diaphragms ordinarily have tobe made with considerable care in order to operate properly. They areVusuallycomparatively expensive and they are rather difcultev-tormake,if either an extremely Ilarge or` extremely small diaphragm is required.I have found that a comparatively inexpensive diaphram maybe made byplacing a layer of liquid of a color to obstruct light between two 010-tical elements; one having a curved surface and .the other having a flatsurface, so that by applying Ypressuretotlfie optical elements, thediaphragm liquid.. may be excluded from a larger or smaller areaof YanQpeningto in effect vary the size of a lightbeam passing throughthe op-.tical elements. J

Coming. now to the-drawings wherein like reference characters denotelike parts throughout: Fig. 1 is a schematic sectional view showing aliquid diaphragmconstructed in accordance with and embodying a preferredform of my invention; Fig. 2 is a fragmentary sectional view of a liquiddiaphragm constructed in accordance with a second embodiment of myinvention; Fig. 3 isa schematic top plan View ofa liquid diaphragmadjusted to a relatively small aperture;f. -Y ,Y g Fig. 4 isafview's'imilar to Fig. 3'with ythe dia- 5 claims. (ones-c4);

CLI

`tween these two optical members.

phragm adjusted--- to a' Y considerably larger Laperture;A Y 1 i Y ,v .YFig. 5 isa fragmentary detail section showing another embodiment of myinvention; =-Fig. 6 isa fragmentary sectional viewrshowing a 'methodofcorrection which'can be used:in conrnection with a liquid diaphragmconstructed. in #accordance with my invention; and l- -T'is a Viewsimilar to Fig. 6 but, of still 4another Vcorrecting `embodiment of.myinvention Broadly speaking, my invention consists inpro- -yidin'gadiaphragm of a light-obstructing or an opaque liquid, which liquid lillsa space between Ea curved surface optical elementand a flat surfaceoptical element.y The curved surface may leither be cylindrical or.spherical, and it normally contacts with theiiat optical element so.that? all the space betweenthese two elements may be riilledwiththeopaque liquid. z Since the fiatoptical elementY is made comparativelyythin and may ilex by applying pressure to the rigid optical element,`the cross section of the light-obstructing liquid isfchanged and itmaybe made to produce .either a large or small aperture with compara-,f-tively slight changes in pressure between the two felements. L f

.One embodimentof my invention is shownr in Fig. 1 wherein a light beamis controlled; `lthis :beam being Vused,`in the present instance, Yin acontinuous printingrinachine.l A Anegative N is Ipassed throughai'llmgateconsisting of aperture plates Igand 2 in the direction'shownby thexar- A,row preferably continuously moving, so that an which .alens Ifiivhaving` a front curved surface I I ,may rest; there, being alayer1 I2 `of fluid Abe- The lens I0 `Vmay have a tight connection withthe supporti! throughwa gasket I3. A ring I 4 may berpressed downwardlyby la pair oi-` oppositely-disposed screws I5 passing through thering-like member I6; This member mayfrock upon a screw I'I as a1fulcrum,and-a secondr screw I8 passesy through -thefopening I9in thearm 20 of this member.

A. Arm-y20 forms any armature fory the rmagnets 2 I carried; byV asupporting.brackt k2ir` and connected by wires 23 and 24 to a startingswitch 25, a source of power 26, here shown as a battery, and adiaphragm-adjusting resistor 21. The adjusting arm may be arranged overa diaphragm scale 28, graduated into units of diaphragm values, so thatan operator may, by adjusting the diaphragmadjusting resistor 21, afterhaving closed switch 25, create the desired amount of pressure on thering i4 t 'cause the lens'elementto 'press against the optical flat andsqueeze out the lightobstructing fuid to form an aperture of the desireddiameter. For instance, Fig. 3 shows the aperture A to be of a smallsize as, for instance, f/22, and Fig. 4 shows the diaphragm A opened upto a predetermined extent such as to a predetermined value of f/4.

I have found that quite a large number of different materials aresuitable for forming the light-obstructing liquid, and it is generallypreferable to utilize a dye for this purpose. Many dyes will transmitonly part of the spectrum and obstruct other rays and, under somecircumstances, t may be desirable to change the color of the dye 'tovarious-known types of filter dyes butfin generalyI prefer to have thefluid which forms the diaphragm as nearly opaque as possible.' -=It may'happenthat the smallest diameter of the diaphragm =may -transmit somesmall amount' of light rays whichaifect sensitive film, but I have foundthat this is not particularly materiallv i Obviously-various'ways may beused for creating the pressure between the optical elements as, forinstance, in Fig.` 2,1 the ring I4 may be compressed by a hinged member3D, mounted on the hinge pin '3`|.connected to a support 32 and carryingadjusting screws 33. 'One of these screws rests 'on each side-of thering I4 and this ring is connected toia rack'34 having teeth 35 meshlngwithA the worm' 36 carried by a shaft 31. This shaft may beadjusted' byahandwheel 38. Both of thesetypes 'of adjustments'are useful in verticalVmachines where the diaphragm may be spaced some' distance fromthelfloor because obviously the operating r'nexnb'ersV of these twosystemsthe diaphragm-adjusting resistor 21 of Fig. 1 or the handwh'eel"385 (if-Fig. `ZLmay' be moved from a distant ipinti- Y Still"'anothei`form -of adjusting member is shown in Fig. wherein a lens 40 has acurved surfaceY 4|` normally resting' on the Yflat plate 42.

Both these-optical members are carried by the ring 43 a-ndmadefluid-tight as by means of a gasket 44iso`as to hold a layer 45 oflight-obstructing fluidA between'thes'e optical elements. In this-instance Ilprovide a channel 46 to a reservoir 41 ofthelight-obstructing fiuid; this reservoir having aexible portion` 48 toreadily compensate vfor expansion' and contraction.y Member 43 isthreaded at49 tov receive the thread 50 of the pressure ring'5l. -Thisring has a iiange 52 resting on the lens V40. `In addition, it isprovided witlra knurle'd operating ring 53 and a pointer '54 which 'liesover a diaphragm scale 55. By turning the knurled ring 53, more or lesspressure may' be' applied to the lens 40, thus iiexing the plate 42l andcausing the light-obstructing fluid 45 to moveto or from the axis of theoptical element,`thuslefectively changing the diameter of thediaphragm.'

I have found that where the curved surface of the lens is a sphericalsurface, or an aspherical one for that matter, the light-obstructingliquid will maintain a'circular shape, so that the effectivelapertureoa'nuid' diaphragm is always substantially round. If I should desire touse a cylindrical lens, the diaphragm, of course, would be rectangularaccording to the shape of the cylindrical lens which would, of course,deect the optical flat in one direction only. For most purposes,however, I prefer to provide a spherical or aspherical surface on thelens element.

Formany`purposesas. for instance for the printer shown `diagrammaticallyin Fig. l, the fact that the optical elements have some power is notimportant. As a matter of fact, I have found that very little power isnecessary as the lens may be of one-fourth or one-half diopter, althoughthis, of course, may vary in accordance with the -purpose'for which thedevice is used. If, however,v it should be undesirable to have powerinthe liquiddiaphragm, this can be overcome by providing a second liquidlayer. Referring to Fig. 6, the lens member 6D has a cylindrical surface6I which normally touches the upperisurface ofthe plain glasshplate 62;lthere being a layer of light-obstructing uid 63 between theremaining'portions of these two opticalelements. Eachtime pressure isapplied inthe direction shown by the arrows=to the lens 50, the plate 62is deflected and the cross-sectional shape of the liquiddiaphragm"iisaltered.V f I can provide a second lenselement 64 having acurved surface 65, and-I may place-a liquidlayer 66 between this elementand the glassfiats.y I prefer generally to provide this liquid layerof aclear,V or lighttransmitting liquid, and usuallyf'it'is desireable tomake it. the same liquidthat'is'used asa solvent for the dye'light-obstructing fluid.' For instance, if the light-'obstructing.layer 63 is of a dye dissolved inacetone, thenv acetone may beconveniently used vfor the clear layer. of liquid 65 without-the 'dyebeing-:added By the proper selection of refractive index of the thirdoptical element 64 and of the liquid layer 66, the power which otherwisemightlexist inthe opticalelement can be eliminated. In anotherembodimentof my invention, show'ndnFigJ'I, lens -10 has a spherical surface 1lresting'lagainst the upper surfacel of a seoond=opticalmernber 12: whichis a fiat, there' being a layer of light-obstructing huid 13 between therstand second optical elements. Here, the third opticalelement 14 mayalso by a glass hat and the layer 15 of liquid between the second-andthird optical elements is a light-transmitting liquid.l Thus, ifpressure is applied to the flens 10, deflecting the glass plate 'i2 toalter the crosssection of the light-obstructing liquid layer 13 andthereby -the effective diameter of the diaphragm, the transparent orlighttransmitting layer 15" of liquid lbetween the second andthird'opticallelements is also altered in cross section by a likeamount. Here again, by properly selecting the refractive indices of theoptical elements `andthe transparent'liquid' layer, any power ofthe twooptical elements 10 and 12 may be offset. Thisl isdesirable if a liquiddiaphragm is to be used in an objective because if there were power inthe diaphragm optical elements themselves,`they wouldspoil thecorrections of the objective."

In any of the -embodiments-of'my invention I, of course, provide'someform of `expansion chamber for the liquid layers, both'thelight-obstructing liquid andthe light-transmitting liquid layers, sothat the material does not dry out and so that it may expand andcontract under the pressure applied to the lens which -forrns the firstoptical element of the diaphragm. It is, of course, necessary that oneof= the optical elements of the diaphragm is comparatively rigid andthat one may fiex. I prefer to have the rigid member the member havingpower and the flexible member the glass fiat because this appears toproduce the most desirable results.

As pointed out above, I usually prefer to provide a diaphragming liquidwhich is as nearly opaque as can be obtained for general purposes,although with some types of materials it is quite possible that dyeswhich are only partially opaque to the spectrum might serve just assatisfactorily, particularly as certain types of photographic materialare color blind through certain ranges of the spectrum. It will readilyoccur to one skilled in the art to provide a liquid diaphragm of a dyewhich will mask olf the light rays to which the film may be sensitive tothe desired degree, so that by adjusting the liquid diaphragm to a knownvalue, exactly the same amount of light may be passed each time thediaphragm is so set.

Having thus described my invention what I claim is new and desire tosecure by Letters Patent of the United States is:

1. An optical diaphragm comprising a pair of member, a layer oflight-obstructing fluid between the curved and flat surfaces forming adiaphragm, and means to vary the pressure between the contacting curvedand fiat surfaces to flex the at surface and to vary the shape of thelight-obstructing uid forming the diaphragm, a third light-transmittingmember adjacent to, but spaced from, the flat light-transmitting memberand a layer of liquid between, adapted to change in shape when pressureis applied to the curved and flat surfaces to flex the flat surface andto alter the diaphragm shape, said layer of liquid last referred tooptically compensating for the power of the system.

2. An optical diaphragm comprising a first light-transmitting memberhaving a curved surface, a second light-transmitting member comprisingan optical flat adapted to flex under pressure, a layer oflight-obstructing fluid therebetween, a third light-transmitting memberspaced from the second, a layer of light-transmitting iluid between thesecond and third members constituting a variable power fluid lens, andmeans for iiexing the second light-transmitting optical fiat member fromits optically flat position, thereby altering the shape of both thelightobstructing and light-transmitting uid layers as thelight-obstructing fluid layer changes to alter the effective diaphragmopening due to flexing of the optical fiat from its normal flatcondition.

3. An optical diaphragm as defined in claim 2 characterized by thelight-obstructing fluid comprising a dye in a solvent.

4. An optical diaphragm as defined in claim 2 characterized by thelight-obstructing fluid comprising a dye in a solvent, thelight-transmitting fluid comprising the same solvent but without a dye.

5. An optical diaphragm comprising a lens having a convex surface and asheet of flexible transparent material, means for mounting the sheet ofexible transparent material, a mount for the lens positioned to hold theconvex surface of the lens in contact with the sheet of ileXibletransparent material, and a light-obstructing fiuid filling the spacebetween the lens and sheet forming a diaphragm thicker at the edges thanat the center thereof in cross section, and means for pressing the lensand sheet together to ex the transparent sheet material to vary theeffective size of the diaphragm by changing the cross section of thelight-obstructing fluid.

HENRY HARRISON.

REFERENCES CITED UNITED STATES PATENTS Name Date Hopkins Nov. 11, 1924Chromy June 10, 1930 Number

